Rotary dancer for a packaging machine

ABSTRACT

The present invention relates to a packaging machine ( 1 ), which unrolls a lower film web ( 8 ) from a supply roller ( 52 ) and transports it intermittently or continuously along the packaging machine and thereby forms packaging recesses ( 6 ) in the lower film web ( 8 ) in a forming station ( 2 ), after which the packaging recesses are filled with a product ( 16 ) to be packaged, wherein an upper film web ( 14 ) is subsequently sealed onto the lower film web ( 8 ) in a sealing station ( 15 ), wherein the upper film web ( 14 ) is unrolled from a supply roller ( 22 ). Provided downstream of the supply roller is a dancer ( 20 ), which has at least one, preferably two rollers ( 23.1, 23.2 ), which are provided on a linkage ( 23.4 ), which, driven by a rotary drive, rotates about an axis of rotation ( 23.3 ) and thereby stores a certain length of film web ( 8, 14 ) and/or produces a certain tension in the film web ( 8, 14 ).

The present invention relates to a packaging machine having a dancer, a sheet-material brake, an adhesive-bonding table and/or a sheet-material roll.

Such packaging machines are known from the prior art. In the case of said packaging machines, a lower sheet-material web is unrolled from a supply roll and transported preferably in an intermittent manner along the packaging machine. In a forming station, in the first, instance a packaging cavity is formed in the lower sheet-material web, said packaging cavity then being filled with a product, in particular a food. Thereafter, the packaging cavity is closed by an upper sheet material, which is sealed onto the lower sheet material, in a sealing station. The sheet-material web here is likewise unrolled from a supply roll. A dancer is provided between the supply roll and the sealing station, and has to be adapted to the forward pull executed by the lower sheet-material web during an advancement operation. For this purpose, it has been necessary in the past to provide a dancer which is designed individually in each case for the packaging machine, and this has been found to involve very high outlay.

It was therefore the object of the present invention to provide a packaging machine which does not have the disadvantages of the prior art.

The object is achieved by a packaging machine which unrolls a lower sheet-material web from a supply roil and transports it in an intermittent or continuous manner along the packaging machine and, in a forming station, forms packaging cavities in the lower sheet-material web, said packaging cavities then being filled with a product, wherein, thereafter, in upper sheet-material web is sealed onto the lower sheet-material web in a sealing station, wherein the upper sheet-material web is unrolled from a supply roll, and a dancer is provided downstream of at least one supply roll, said dancer having one roller, preferably two rollers, which are provided on a linkage which, driven by a rotary drive, rotates about a rotary pin and thus stores a certain length of sheet-material web and/or generates a desired level of tensioning in the sheet-material web.

The present invention relates to a packaging machine in which a lower sheet-material web, in particular a plastics sheet-material web, preferably having a width between 200 mm and 1 m or more, is unrolled from a supply roll and transported preferably in an intermittent manner along the packaging machine. In a forming station, said lower sheet-material web is then first of all heated and a thermoforming tool is used to form packaging cavities in the lower sheet-material web. It is usually the case that a plurality of packaging cavities, arranged in a so-called format, are formed at the same time and, thereafter, are transported along the packaging machine at the same time. Subsequently, each packaging cavity is filled with a product, in particular a food, for example sausage, ham or cheese, and, in a next step, is closed by an upper sheet material in a sealing station, wherein the upper sheet material is usually sealed onto the lower sheet-material web. The pack completed in this way is then separated. The upper sheet-material web is likewise unrolled from a supply roll.

According to the invention, a dancer is provided downstream of the respective supply roll, as seen in relation to the transporting direction of the respective sheet-material web, at least in the region of the upper sheet-material web, but possibly also in the region of the lower sheet-material web, said dancer having preferably two rollers, which are provided on a linkage which, driven by a rotary drive, rotates about a rotary pin and thus stores a certain length of sheet material and/or generates the desired level of tensioning in the sheet material web. The dancer is consequently suitable as a material store, since the operation of unwinding the sheet-material web from the supply roll has a different speed profile from the operation of advancing the sheet-material web.

A linkage within the content of the invention is any desired component which is made up, for example, of rods, tubes, profiles and/or metal sheets and/or plates. However, it is also possible for the linkage to be a primary-formed component that has subsequent work carried out on it if appropriate. At least two rotatable, in particular non-driven, rollers are arranged on said linkage.

The dancer is preferably provided with a means which senses the angular position of the linkage. As result, a control unit to which said means is connected knows the length of the sheet-material web located in the dancer and/or the control unit can calculate, for example, the number of degrees by which the position of the linkage has to be changed in order to achieve a certain level of tensioning in the sheet material.

According to the invention, the dancer, in particular the linkage, is provided with, and/or connected to, a rotary drive, which rotates the linkage, and therefore the two rollers, simultaneously about the rotary pin of the linkage and thus changes the length of the sheet-material web stored in the dancer and/or the level of tensioning of the sheet material. The rotary drive is preferably a pneumatic drive, a servomotor or a stepping motor. For the case where the rotary drive is a pneumatic drive, the pressure is preferably adapted in dependence on the angular position of the linkage. This can take place, for example, by way of a proportional valve. Starting from a zero position, the pressure preferably drops and then increases again up to the end position of the linkage. The pressure profile particularly preferably corresponds to a cosine curve, wherein it should particularly preferably be the case that the pressure is not zero at any point in time.

According to a preferred embodiment of the present invention, at least one roller of the dancer is, preferably all the rollers of the dancer are, mounted by means of bearings at the two opposite ends. This gives rise to a more uniform load distribution along the roller. In particular, the bending of the latter is at least reduced and/or largely symmetrical over the width of the sheet material, which is of critical importance in particular in the case of wide sheet-material webs, preferably >400 mm, in order to achieve a tensioning profile which is as constant as possible, and/or at least symmetrical, over the entire width of the sheet-material web, i.e. in a direction transverse to the transporting direction thereof.

The two bearings of each roller are preferably supported on a wall located on one side of the sheet-material web. This means that the region beneath the dancer is freely accessible and can be seen and, if required, worked on.

The dancer, in particular the linkage, is preferably fully enclosed by a housing. The sheet-material web passes into the housing, and out of the housing, through slots. The dancer is thus protected against splashing, for example during cleaning.

The surrounding machine region in which the dancer is arranged is particularly preferably fully enclosed by a housing. As an alternative, or in addition, the housing is provided such that, once an access door has been opened, the entire dancer, but in particular the linkage, is freely accessible.

The rollers, in particular the rotary bearings thereof, are preferably grounded, and this means that there is no undesired spontaneous discharge on account of electrostatic charging. The rotary bearings are preferably rolling-contact bearings.

According to a further invention-specific or preferred subject matter of the present invention, a sheet-material brake is provided downstream of the dancer, as seen in relation to the transporting direction of the upper and lower sheet-material webs, but in particular the upper sheet-material web, said sheet-material brake being required in particular for the purpose of positioning the upper sheet-material web on the lower sheet-material web, for example for the purpose of positioning printed patterns which are often provided on the upper sheet-material web.

Said sheet-material brake is preferably mounted by means of bearings in a pivotable manner, in particular such that it can be pivoted about a vertical pin and/or a horizontal pin. It is thus possible for the sheet-material brake to be pivoted from its orientation in the production position, i.e. in a direction transverse to the transporting direction of the lower sheet-material web, into a position in which it is, for example, parallel to the transporting direction of the lower sheet-material web, this region therefore being accessible in order to be inspected or worked on. A connecting means, in particular a latching means, is preferably provided opposite the vertical rotary pin, on the other side of the sheet-material web, and can be used to fix the sheet-material brake in its production position in a direction transverse to the transporting direction of the lower sheet-material web. Said connecting means is actuated preferably without any tools being used. Furthermore, the sheet-material brake preferably comprises a first part and a second part, which are connected to one another, wherein the first part and the second part have provided between them a gap, through which the sheet-material web, in particular the upper sheet-material web, runs during production and in the region of which is provided a braking means, for example an inflatable hose, by means of which the transportation of the upper sheet material can be braked, as result of which the sheet-material web is stretched. It is preferable, then, for the second part to be mounted on the first part in a rotatable manner, in particular about a vertical rotary pin, or vice versa. It is thus possible, in particular for the purpose of threading the sheet-material web in, for the second part to be rotated away from the first part, for the sheet-material web to be placed in position, and for the second part then to be rotated back again and arrested in a position parallel to the first part. This preferred embodiment of the present invention makes it considerably easier for the sheet-material web to be threaded into the sheet-material brake.

Yet another invention-specific or preferred subject matter of the present invention is a packaging machine which has a cutting and adhesive-bonding table. Such a cutting and adhesive-bonding table is required, in particular, for changing over a sheet-material roll, in which operation the end of the used-up sheet-material roll is connected to the start of the new sheet-material roll.

The cutting and adhesive-bonding table preferably has at least one aperture, preferably more than one aperture, connected to an, in particular joint, vacuum means. By virtue of said vacuum means, the two sheet-material webs which are to be joined together are fixed on the table and can be worked on accordingly. As an alternative, it is also possible to fix the sheet-material web using adhesive pads or an inflatable hose.

The apertures can preferably be provided, in an optional and reversible manner, with a suction-attachment means or with a dummy plug. The suction-attachment means preferably has a perforated plate. The perforated plate can be used to transfer the vacuum onto the respective sheet-material web. A dummy plug covers the aperture so that, in this region, the sheet-material web is not subjected to any suction-attachment force. The positioning of the apertures and the usage of the suction-attachment means and of the dummy plugs make it possible for the cutting and adhesive-bonding table to be adapted, for example, to the width, but also to the nature, of the respective sheet-material web, without any need for different cutting and/or adhesive-bonding tables having to be provided for the respective sheet-material web. The apertures are preferably arranged along a line, in particular in an equidistant manner. The cutting and adhesive-bonding table particularly preferably has at least two, in particular parallel, rows of apertures. As an alternative, or in addition, to the perforated plate, it is also possible to use a slotted nozzle or a porous, for example sintered, material.

The cutting and adhesive-bonding table is preferably provided in a pivotable and/or easily installable manner on the packaging machine, which improves the accessibility of the latter. The cutting and adhesive-bonding table is preferably arranged upstream of the dancer, as seen in relation to the transporting direction of the sheet-material web, but is particularly preferably arranged directly behind the sheet-material roll.

Yet another invention-specific or preferred subject matter of the present invention is a packaging machine which has rollers in the case of which the bearing seat is connected to the rotary body of the roller by means of a laser weld seam. This invention-specific or preferred embodiment of the invention has the advantage that the rollers exhibit considerably less thermal distortion than rollers according to the prior art. Nevertheless, they are completely water-tight.

It is preferably the case that, upstream of the sealing station, the upper sheet-material web runs, at least in part, parallel to the machine frame and parallel to the transporting direction of the lower sheet-material web. As an alternative, it is also possible for the running direction of the upper sheet-material web to be arranged, in part, at 90 degrees to the machine frame, as a result of which use can be made, for example, of particularly large, and therefore for the most part also heavy, supply rolls, which have a high capacity for storing sheet material.

Yet another preferred subject matter of the present invention is a packaging machine which has at least one labeler and/or a printer, arranged preferably downstream of the supply roll and upstream of the dancer.

Yet another preferred subject matter of the present invention is a packaging machine which has an auxiliary withdrawal means for the upper sheet material, said withdrawal means driving the upper sheet-material web, prior to it entering into the sealing station, preferably synchronously with the intermittent transporting movement of the lower sheet-material web. For example in the case of sensitive, e.g. very thin, sheet materials and/or sheet materials with rubber-like expansion behavior, this therefore minimizes the tensile forces acting on the new sealing seam and thus possible creasing in the region of the sealing seam. The upper sheet-material web here is clamped preferably between two deflecting rollers which are prestressed in relation to one another, and of which at least one deflecting roller is driven. For the purpose of threading the upper sheet-material web in, it is possible to release the prestressing between the two deflecting rollers and to move the latter apart from one another preferably by a reasonable amount.

Yet another subject matter of the present invention is a method of threading a sheet-material web into a dancer, wherein the rollers of the dancer can be transferred into a threading-in position. In this threading-in position, the sheet-material web can be drawn essentially along a straight line, preferably vertically, through the dancer and need not be guided, with high outlay, around the rollers. This is advantageous, in particular, in the case of a dancer which has rollers which are mounted by means of bearings at both ends. As soon as the sheet-material web is threaded into the dancer, the latter assumes its zero position and, subsequently, its storage position.

What has been said in relation to the packaging machines according to the invention applies in equal measure to the method according to the invention, and vice versa.

It is preferably the case, for the purpose of threading the sheet-material web into the sheet-material brake, that one part of the sheet-material brake is moved away, in particular rotated away, and then, as soon as the sheet-material web extends through the sheet-material brake, is rotated back again.

The inventions will be explained hereinbelow with reference to FIGS. 1 to 12. These explanations are given merely by way of example and do not limit the general concept of the invention. The explanations apply in equal measure to all the subjects of the present invention.

In the figures:

FIG. 1 shows the packaging machine according to the invention,

FIG. 2 shows the dancer,

FIG. 3 shows the dancer according to FIG. 2 in its threading-in position,

FIG. 4 shows the dancer in a production position,

FIG. 5 shows how the dancer is suspended on the wall 26,

FIG. 6 shows the arrangement of the sheet-material brake in the packaging machine,

FIG. 7 shows the sheet-material brake according to FIG. 6 in a service position,

FIG. 8 shows the second part of the sheet-material brake being pivoted away from the first part,

FIG. 9 shows the cutting and adhesive-bonding table,

FIG. 10 shows a suction-attachment box, and

FIGS. 11-13 show the laser-welded roller.

FIG. 1 shows the packaging machine 1 according to the invention, which has a thermoforming station 2, a filling station 7 and a sealing station 15. A lower sheet-material web 8, in this case a plastics sheet-material web 8, is withdrawn from a supply roll 52 and transported from right to left in a cyclic manner along the packaging machine according to the invention. Over the course of a cycle, the lower sheet-material web 8 is transported onward by one format length. For this purpose, the packaging machine has two transporting means (not illustrated), in the present case two endless chains, which are arranged to the right and left of the lower sheet-material web 8. Both at the start and at the end of the packaging machine, in each case at least one gearwheel is provided for each chain, the respective chain being deflected around the gearwheel. At least one of these gearwheels is driven. The gearwheels in the entry region and/or in the exit region can be connected to one another, preferably by a rigid shaft. Each transporting means has a multiplicity of clamping means, which engage the lower sheet-material web 8 with clamping action in the entry region 19 and transmit the movement of the transporting means to the lower sheet-material web 8. The clamping connection between the transporting means and the lower sheet-material web 8 is released again in the exit region of the packaging machine. A heating means 13 is provided downstream of the entry region 19 and heats the sheet-material web 8, in particular when the latter is at a standstill. In the thermoforming station 2, which has an upper tool 3 and a lower tool 4, the latter being in the form of the packaging cavity which is to be produced, the packaging cavities 6 are formed in the incipiently heated sheet-material web 8. The lower tool 4 is arranged on a lifting table 5, which, as symbolized by the double arrow, can be adjusted vertically. Prior to each advancement of the sheet material, the lower tool 4 is lowered, and is then raised again. Further on in the packaging machine, the packaging cavities are then filled, in the filling station 7, with the product 16. In the subsequent sealing station 15, which likewise comprises an upper tool 12 and a vertically adjustable lower tool 11, an upper sheet material 14 is sealed on the lower sheet-material web 8 with material bonding. It is also the case in the sealing station that the upper tool and/or the lower tool are lowered and/or raised prior to and following each sheet-material transporting operation. It is also possible for the upper sheet material 14 to be guided in transporting means and/or to be transported by transporting chains, wherein said transporting means then extend only prior to the sealing station and possibly downstream. Otherwise, what has been said in relation to the transporting means of the lower sheet material applies. It is also possible for the upper sheet material to be incipiently heated by a heating means and thermoformed. For the sealing operation, the lower tool 11 provided is, for example, a heatable sealable frame which, for each packaging cavity, has an opening, into which the packaging cavity penetrates during the sealing operation, i.e. during the upward movement of the lower sealing tool. For sealing purposes, the upper and the lower sheet-material webs are pressed together between the upper tool 12 and the lower tool 11 and bond under the influence of heat and pressure. Following the sealing operation, the tools 11, 12 are moved apart vertically from one another again. A dancer 20 is provided between the supply roll 21 and the sealing tool, said dancer compensating for the intermittent advancement of the lower sheet material 8, and thus for the intermittent withdrawal of the upper sheet-material web 14. The dancer can be used as a sheet-material-web store and/or for the purpose of generating a certain level of tensioning in the sheet material. A person skilled in the art will be aware that a plurality of upper sheets may be present, for example in the case of a multilayered pack or a pack with a plurality of upper sheets. In this case, a dancer is preferably provided along the course of each upper sheet. A person skilled in the art will also be aware that a dancer may also be provided in the region of the lower sheet material, preferably downstream of the supply roll 52. Prior to and/or during the operation of sealing the upper sheet material to the lower sheet material, gas exchange preferably takes place in each packaging cavity. For this purpose, the air present in the packaging cavity first of all is partially extracted by suction and then is replaced by a replacement gas. For this purpose, in the region of each format, holes are made in the lower sheet-material web, in the region of the transporting chains, and the air between the sheet-material webs 8, 14 is extracted by suction, and the replacement gas is then blown in, through said holes. Further on in the packaging machine, the completed packs are separated, which in the present case takes place using the cross cutter 18 and the longitudinal cutter 17. The cross cutter 18, in the present case, can likewise be raised and lowered by means of a lifting device 9.

FIG. 2 shows the supply roll 21, from which in the present case the upper sheet-material web 14 is unrolled. A person skilled in the art will be aware that what is said hereinbelow also applies analogously to the lower sheet-material web 8. The dancer 20 is provided downstream, as seen in relation to the transporting direction of the sheet-material web 14, said dancer having in the present case two fixed-location rollers 22, between which is provided the rotary part 23, which, being drivable by a drive, is provided for rotation as a whole about a rotary pin 23.3. Said rotary part has a linkage 23.4, on which the rotary pin 23.3 is arranged and which has two rollers 23.1, 23.2, which in the present case are provided opposite one another and in a rotatable manner, at the same distance from the rotary pin, on the linkage 23.4. The rollers 23.1, 23.2 are preferably not driven. In the present case, the entire dancer 20 is arranged in a housing 24 and is thus protected against undesired intervention on the part of a worker. It is also possible, however, for the housing and/or the load-bearing basic structure thereof to perform load-bearing functions of the dancer and/or to provide protection against undesirable cleaning agents.

FIGS. 3 and 4 explain the functioning of the dancer. FIG. 3 illustrates the dancer in its so-called threading-in position. In comparison with the illustration according to FIG. 2, the rollers 23.1, 23.2 or the means connecting the same, in this case the linkage 23.4, have/has been rotated in the counterclockwise direction about the rotary pin 23.3. This results in a gap, in this case a vertical gap, between the upper rollers 22, 23.1 and the lower rollers 22 and 23.2, and the sheet-material web 14 can readily be fitted through said gap, which considerably simplifies the operation of threading the sheet-material web in, in particular because the rollers 22, 23.1, 23.2, according to a preferred embodiment of the present invention, are mounted by means of bearings at their two ends. As soon as said threading-in operation has been completed, the rollers 23.1 and 23.2 are rotated again, this time in the clockwise direction, about their point of rotation 23.3 and the dancer can be used as a sheet-material store. FIG. 4 shows the store in a partially filled state. Since the rollers 23.1 and 23.2 have been rotated in the clockwise direction in comparison with the illustration according to FIGS. 2 and 3, the length of sheet material which is located in the store has been increased. As will be readily clear to a person skilled in the art, the length of sheet material stored depends on the angle of rotation α of the rotary part 23 between 0 and more or less 180°. As already explained, the rotary part 23 is driven by means of a motor. This motor may be a servomotor, or actuating motor, or a stepping motor or a pneumatic drive. In the case of the pneumatic drive, the pressure by which the drive is driven is regulated preferably in dependence on the angular position of the rotary part 23. Starting from the zero position (cf. FIG. 2), in which the dancer stores barely no sheet material, if any at all, and the rollers 23.1 and 23.2 axe located, in the present case, essentially in a lines with the rollers 22, the pressure increases in the first instance to a pronounced extent, in particular up to a position of the rollers 23.1 and 23.2 of α=20-36°, and then remains essentially constant in order thereafter, preferably from an angle of α=40°, to drop until the dancer reaches its end position (dancer full), which is the case at α=approximately 170-180°, in particular α=176°. During dynamic operation, the dancer preferably does not fall below an angular position of α=20-30°, in particular α=30°. A control/regulating unit connected to the packaging according to the invention knows, at any point in time, the rotary position in which the rotary part 23 is located and, accordingly, the length of sheet material stored in the dancer. Accordingly, the drive of the rotary part 23 is activated so as to leave this stored length as it is, to increase it or to reduce it. It is also possible, however, for the drive of the rotary part 23 to be used to change the level of tensioning in the sheet-material web, by virtue of the angle of rotation of the rotary part being changed while the sheet-material roll 21 is at a standstill and the sheet-material web 8 is at a standstill, wherein, in the present case, the level of tensioning increases during rotation in the clockwise direction and the level of tensioning in sheet-material web 14 decreases during rotation in the counterclockwise direction. It is also possible for the level of tensioning in the sheet-material web to be changed or kept constant while the sheet material roll 25 is being moved. Measuring means for measuring the level of tensioning in the sheet material, and regulating the same accordingly, may be provided in the region of the dancer or in the region of the sheet-material web.

FIG. 5 shows how the dancer 20 is suspended on the packaging machine. In the present case, the dancer is provided in the region of the upper sheet-material web 14 and, accordingly, is provided on an arm or a metal, sheet or a wall or a framework 26—hereinbelow referred to as installation means 26—above the lower sheet-material web 8. The dancer 20 as a whole is provided on the installation means 26 in the present case by way of four suspension means 25. These suspension means are designed in the present case in the form of pull/push rods 25 and extend horizontally through the entire width of the dancer or of a housing 24 and/or of the load-bearing basic structure thereof (not illustrated). The dancer as a whole is surrounded by the housing 24, which has an end-side door 28, which can be swung open around the hinge 27. It is also the case that a cover 29 is preferably provided on the housing, and said cover can be opened, in particular pivoted open, about a horizontal axis. As can be seen by the example of the entry roller 30, each roller in the region of the dancer is preferably mounted by means of bearings at its two opposite ends on the dancer housing 24 and/or on the load-bearing basic structure thereof and/or on the linkage 23.4. This gives rise to significantly better and more symmetrical load distribution in the region of the rollers. In particular, the rollers bend to a lesser extent, and this makes for more uniform unwinding of the supply rolls. It is also the case that the rotary part 23 has a rotary bearing preferably at each of its two opposite ends, said rotary bearings each being supported on the housing 24 and/or on load-bearing basic structure thereof and therefore on the suspension means 25 of the dancer. It is nevertheless the case that the dancer 20, or the housing thereof, is supported only on one side of the sheet-material web by way of the installation means 26, and this means that the region beneath the dancer 20 is easy for a worker to see and access.

FIGS. 6 and 7 show the sheet-material brake 32 according to the invention. A sheet-material brake is provided, as seen in relation to the transporting direction of the respective sheet-material web, downstream of a possible dancer and serves to stretch in particular the upper sheet-material web, so as to orient the upper sheet-material web relative to the lower sheet-material web prior to these being sealed, so that for example a printed pattern provided on the upper sheet-material web matches the position of the packaging cavity provided in the lower sheet-material web. In the present case, the sheet-material brake is mounted by means of a rotary and/or pivot bearing 34 on one side of the lower sheet-material web 8, in this case on an installation means 26. A bearing 33 is located on the opposite side of the lower sheet-material web 8, said bearing having a closure 36, in particular a quick-action closure, by means of which the end of the sheet-material brake 32 there can be connected to the frame of the packaging machine. Said closure 36 preferably has a handle 35, by means of which the closure can be in particular unlocked. Subsequent locking takes place preferably automatically, in particular by way of a snap-action or latching mechanism. Following actuation of the handle 35, the two parts of the closure 36 can be separated from one another and the sheet-material brake as a whole can be pivoted about the rotary bearing 34, as illustrated in FIG. 7, from a production position in a direction essentially transverse to the transporting direction of the lower sheet-material web (FIG. 6) into a service position essentially parallel to the transporting direction of the sheet-material web. FIG. 7 illustrates the transition of the sheet-material brake 32 from the production position into the service position.

As can be gathered from FIG. 8, the sheet-material brake in the present case comprises essentially a first part 32.1, on which the second part 32.2 is mounted in a rotatable manner by means of a rotary pin 38. An arresting means 37, in this case provided by a pin, is illustrated on that side of the two parts 32.1, 32.2 which is located opposite the rotary pin 38, and said arresting pin can keep the two parts in a parallel position—the production position—in relation to one another. During production, the two parts 32.1, 32.2 have located between them a gap, through which the sheet-material web, in particular the upper sheet-material web 14, is guided. One of the two parts contains a pressure-exerting means, for example a hose, of which the circumference can be changed and which thus changes the size of the gap and therefore pushes the sheet-material web against the other part, as result of which the friction between the sheet-material web and the brake 32 increases or decreases and, accordingly, provides for braking to a greater or lesser extent. In order for the operation of threading the sheet-material web 14 into the gap to be facilitated prior to the beginning of production, the closure 37 is opened, in this case the part 32.2 is rotated about the rotary pin 38, and then the sheet-material web is positioned on the first part 32.1. The second part 32.2 can then be rotated back again to its position parallel to the part 32.1 and secured again in this position by means of the closure 37. A person skilled in the art will be aware that it is also possible for the other part to be moved in each case.

FIG. 9 shows the cutting and adhesive-bonding table 39. In the present case, the latter has two entry rollers 42 and an exit roller 43, although these need not necessarily be present. The cutting and adhesive-bonding table 39 also has optionally two clamping means 40, 41, which can be rotated, for example about an axis, from a clamping position into a non-clamping position, and vice versa, and can be used to fix the respective ends of the sheet-material webs which are to be connected. According to the invention, the adhesive-bonding table has a plurality of apertures. The present case provides for two, in this case parallel, rows each with nine, in this case equidistant, apertures, which are provided preferably to the right and left of a cutting guide 46. The cutting guide serves as a guide/abutment, for example for a blade, in order for it to be possible for the respective sheet-material web to be cut off along a straight cutting line. Each aperture can be connected here, by means of a channel, to a vacuum means, preferably a joint one, in particular a vacuum pump. It is also possible for each aperture to be provided optionally with a suction-attachment box 44 or a dummy plug 45, it therefore being possible, in accordance with the width of the sheet-material web and/or the nature of the sheet-material web, to select the region in which the vacuum is applied. The suction-attachment boxes 44 are provided, for example, with a perforated plate 44.1, through which the vacuum acts on the sheet-material web and draws the latter in the direction of the cutting and adhesive-bonding table 39, and fixes it there. Only a slight vacuum, if any at all, is applied in the region of the dummy plugs 45. In the present example, the suction-attachment boxes and the dummy plugs are provided in an alternating manner over the entire width of the adhesive-bonding table. In the case of sheets of a comparatively small width, it makes sense to provide the outermost apertures with a dummy plug, in order to avoid false air being taken in.

FIG. 10 shows, by way of example, a suction-attachment box 44 which can be provided in a reversible manner, preferably without any tools being used, in an aperture. Said suction-attachment box, in the present case, comprises an insert 44.2, in this case a hollow body, and a perforated plate 44.1, which is connected to the insert. The vacuum sucks air through the perforated plate into the interior of the insert 44.2 and from there, by means of bores provided along the circumference of the insert 44.2, into the vacuum channel. The dummy plug is of analogous construction, although the perforated plate is replaced by a non-perforated plate and/or there are no bores along the circumference of the insert 44.2.

FIGS. 11 and 12 illustrate the roller according to the invention. Said roller comprises a rotary body 47, the mounting stub of a rotary spindle being provided at each of its opposite ends. The rotary spindle preferably does not extend through the roller. FIG. 12 illustrates the method of production. The rotary spindle is preferably is provided on a disk-like element, in particular a circular disk or an annular disk. Said disk-like element or the rotary spindle 49 itself is connected to the rotary body by means of a laser weld seam. This means that the roller according to the invention, on the one hand, is of sealed construction. In addition, the laser welding gives rise to only a comparatively small amount of heat being introduced, and therefore the roller is not subject to thermal distortion during welding. Each roller has a rotary spindle 49 on its right and left, it being possible for the roller to be supported on either side, on a housing 24 or the like by means of said rotary spindles. In comparison with being mounted on one side only, this significantly improves the load distribution of the roller. A person skilled in the art will be aware that the rotary spindle may also be a cylindrical indent which accommodates a mounting stub.

All the other rollers provided in the region of the packaging machine according to the invention preferably produced in this way.

FIG. 13 shows the arrangement of a rotary bearing 48, in particular at each of the two ends of a roller. Said rotary bearing 48 is arranged, by means of a bearing seat 50, for example on the frame 55 of the packaging machine and/or on the housing 24 of the dancer. The outer ring of the rotary bearing 48, in this case of a rolling-contact bearing, buts against the bearing seat 50. The inner circumference of the inner ring of the rotary bearing 48 is connected to a rotary spindle 49, which for its part is provided on the roller. The arrangement may also be the other way round. The rotary bearings are provided, in particular, such that they are electrically conductive, and it is therefore not possible for any static charging to occur in the region of the roller.

LIST OF REFERENCE SIGNS

-   1 Packaging machine -   2 Forming station, thermoforming station -   3 Upper tool of the thermoforming station -   4 Lower tool of the thermoforming station -   5 Lifting table, carrier of a tool of the sealing station,     thermoforming station and/or of the cutting device -   6 Packaging cavity -   7 First filling station -   8 Sheet-material web, lower sheet-material web -   9 Lifting device -   10 Drive -   11 Lower tool of the sealing station -   12 Upper tool of the sealing station -   13 Heating means -   14 Upper sheet-material web, cover sheet material -   15 Sealing station -   16 Product -   17 Longitudinal cutter -   18 Cross cutter -   19 Entry region -   20 Dancer -   21 Supply roll of the upper sheet-material web -   22 Roller for deflecting sheet-material web -   23 Rotary part -   23.1 First roller for deflecting sheet-material web -   23.2 Second roller for deflecting sheet-material web -   23.3 Rotary pin -   23.4 Lever, connection, connecting linkage -   24 Housing -   25 Suspension means, pull rods -   26 Installation means, wall -   27 Hinge -   28 Door -   29 Cover -   30 Entry roller -   31 Entry gap -   32 Sheet-material brake -   32.1 First part -   32.2 Second part -   33 Bearing -   34 Rotary and/or bearing pin -   35 Handle -   36 Closure, quick-action closure -   37 Closure -   38 Rotary pin, in particular removable rotary pin -   39 Cutting and adhesive-bonding table -   40 First, clamping means -   41 Second clamping means -   42 Entry roller -   43 Exit roller -   44 Adhering means, suction-attachment box -   44.1 Covering, perforated plate -   44.2 Insert -   45 Dummy plug -   46 Cutting guide -   47 Rotary body -   48 Rotary bearing, rolling-contact bearing -   49 Rotary spindle -   50 Bearing seat -   51 Weld seam, laser weld seam -   52 Supply roll of the lower sheet-material web -   53 First end of the roller -   54 Second end of the roller -   55 Frame 

1. A packaging machine comprising: a forming station; and a sealing station; wherein the packaging machine unrolls a lower sheet-material web from a supply roll of the lower sheet-material web, the packaging machine transports the lower sheet-material web in an intermittent or continuous manner along the packaging machine; wherein packaging cavities are formed in the lower sheet-material web in the forming station, the packaging cavities are then filled with a product, wherein after the packaging cavities are filled with the product, an upper sheet-material web is sealed onto the lower sheet-material web in the sealing station; wherein the upper sheet-material web is unrolled from a supply roll of the upper-sheet material web; wherein the packaging machine comprises a dancer that is provided downstream of at least one of the supply roll, the dancer having two rollers, which are provided on a linkage which, driven by a rotary drive, rotates the dancer about a rotary pin provided between the two rollers; and wherein the dancer stores a certain length of the lower sheet-material web and the upper sheet-material web and/or generates a desired level of tensioning in the lower sheet-material web and the upper sheet-material web.
 2. The packaging machine as claimed in claim 1, wherein the packaging machine comprises a means that senses an angular position of the linkage.
 3. The packaging machine as claimed in claim 1, wherein the rotary drive is a pneumatic drive, a servomotor or a stepping motor, or the rotary drive is a rotary motor with a transmission.
 4. The packaging machine as claimed in claim 1, wherein at least one of the two rollers are mounted by means of bearings at two opposite ends.
 5. The packaging machine as claimed in claim 4, wherein the bearings are supported on a wall.
 6. The packaging machine as claimed in claim 1, wherein the rollers are grounded.
 7. The packaging machine as claimed in claim 1, wherein a sheet-material brake provided downstream of the dancer.
 8. The packaging machine as claimed in claim 7, wherein the sheet-material brake is mounted by means of bearings in a pivotable manner such that the sheet-material can be pivoted about a vertical pin.
 9. The packaging machine as claimed in claim 7, wherein the sheet-material brake has a first part and a second part, which are provided for movement, in particular rotation, in relation to one another by way of a pin.
 10. The packaging machine as claimed in claim 1, wherein the packaging machine comprises a cutting and adhesive-bonding table.
 11. The packaging machine as claimed in claim 10, wherein the cutting and adhesive-bonding table has apertures connected to a vacuum means.
 12. The packaging machine as claimed in claim 11, wherein the apertures can be provided optionally with a suction-attachment means or a dummy plug.
 13. The packaging machine as claimed in claim 1, wherein the packaging machine comprises rollers in a case of which a rotary spindle is connected to a rotary body of a roller by means of a laser weld seam.
 14. The packaging machine as claimed in claim 13, wherein at least one of the rollers has a rotary bearing, which is grounded.
 15. A method of threading a sheet-material web into a dancer, comprising: transferring rollers of the dancer into a threading-in position; and drawing the sheet-material web along a straight line through the dancer for the threading-in.
 16. The method as claimed in claim 15, wherein for threading the sheet-material web into a sheet-material brake, one part of the sheet-material brake is moved away, in particular rotated away, from another part the sheet-material brake.
 17. The packaging machine as claimed in claim 5, wherein the wall is located on one side of the lower sheet-material web or the upper sheet-material web.
 18. The packaging machine as claimed in claim 1, wherein the dancer is fully enclosed by a housing.
 19. The packaging machine as claimed in claim 12, wherein at the adhesive-bonding table, an end of a used-up sheet-material roll is connected to a start of a new sheet-material roll.
 20. A packaging machine comprising: a forming station; a sealing station; a dancer, the dancer comprising two rollers, the rollers are provided on a linkage which, driven by a rotary drive, rotate the dancer about a rotary pin provided between the two rollers, the dancer is fully enclosed by a housing; a means that senses an angular position of the linkage; a sheet-material brake provided downstream of the dancer, the sheet-material brake is mounded by means of bearings in a pivotable manner such that the sheet-material brake is pivotable about a vertical pin; and a cutting and adhesive-bonding table, the cutting and adhesive table having apertures connected to a vacuum means, at the adhesive-bonding table, an end of a used-up sheet-material roll is connected to a start of a new sheet-material roll; wherein at least one of the two rollers of the dancer are mounted by means of bearings at two opposite ends, the bearings are supported on a wall, the wall is located on one side of the lower sheet-material web or the sheet-material web; wherein the rollers are grounded; wherein the packaging machine unrolls a lower sheet-material web from a supply roll of the lower sheet-material web, the packaging machine transports the lower sheet-material web in an intermittent or continuous manner along the packaging machine; wherein packaging cavities are formed in the lower sheet-material web in the forming station, the packaging cavities are then filled with a product; wherein after the packaging cavities are filled with the product, an upper sheet-material web is sealed onto the lower sheet-material web in the sealing station; wherein the upper sheet-material web is unrolled from a supply roll of the upper-sheet material web: wherein dancer that provided downstream of at least one of the supply rolls; wherein the dancer stores a certain length of the lower sheet-material web and the upper sheet-material web and generates a desired level of tensioning in the lower sheet-material web and the upper sheet-material web. 